Microsoft Windows contains a vulnerability in the WINS Server component that could allow an unauthenticated, remote attacker to execute arbitrary code. Updates are available.
Description
Microsoft Windows 2000 SP4 and prior contain a vulnerability in the WINS Server component that could allow an unauthenticated, remote attacker to execute arbitrary code.
This vulnerability exists due to improper boundary restrictions when processing parameters within WINS network packets. An unauthenticated, remote attacker could exploit this vulnerability by sending a malicious network message to the vulnerable system. If successful, the attacker could execute arbitrary code.
Microsoft has confirmed this vulnerability in a security bulletin and released software updates that correct it.
Warning Indicators
Systems running Microsoft Windows 2000 SP4 or prior are vulnerable.
IntelliShield Analysis
An attacker may require access to trusted, internal network segments in order to conduct an exploit attempt. In addition, because affected systems may accept network messages from only trusted replication partners, the attacker may have to spoof the source of malicious messages, increasing attack complexity. If an exploit is successful, the attacker could execute arbitrary code with the elevated privileges of the WINS Server, possibly resulting in a complete system compromise.
The WINS Server is not installed by default on Windows 2000. Only systems with the component installed are vulnerable to exploitation.
The Cisco Applied Intelligence team has created an Applied Mitigation Bulletin to address vulnerabilities that Microsoft disclosed in the August 2009 security bulletin release. This Cisco bulletin, which assists administrators in identifying or mitigating these vulnerabilities using Cisco devices, is available at the following link: Cisco Applied Mitigation Bulletin: Microsoft Security Bulletin Release for August 2009
The update available from Microsoft corrects this vulnerability by performing proper boundary checks on data structures.
Vendor Announcements
Microsoft has released a security bulletin at the following link: MS09-039
Impact
An unauthenticated, remote attacker could exploit this vulnerability to execute arbitrary code with the elevated privileges of the WINS Server component, possibly allowing the attacker to gain complete control over the vulnerable system.
Technical Information
This vulnerability exists due to improper boundary restrictions when processing parameters within WINS network packets. The application fails to properly check input within packets received from a trusted WINS replication partner. The processing of malformed data could trigger an integer overflow, possibly resulting in memory corruption.
An unauthenticated, remote attacker could exploit this vulnerability by sending a malicious network packet to the affected system. The attacker may have to spoof the source of the packet in order to make it appear to the receiving system that the packet originated from a trusted source. When the packet is processed, memory corruption may occur, which the attacker could leverage to execute arbitrary code.
Safeguards
Administrators are advised to apply the applicable software updates.
Administrators are advised to restrict network access on TCP and UDP port 42 to affected systems.
Administrators may consider disabling the WINS Server component.
Administrators may consider using IP-based access control lists (ACLs) to allow only trusted systems to access the affected systems.
Administrators may consider using the Microsoft Baseline Security Analyzer (MBSA) scan tool to identify common security misconfigurations and missing security updates on system endpoints.
Patches/Software
Microsoft customers can obtain updates directly by using the links in the security bulletin. These updates are also distributed by Windows automatic update features and available on the Windows Update website. Microsoft Windows Server Update Services (WSUS), Systems Management Server, and System Center Configuration Manager can assist administrators in deploying software updates.
Signatures
Cisco Systems Cisco Intrusion Prevention System (IPS) 6.0
The security vulnerability applies to the following combinations of products.
Primary Products:
Microsoft, Inc.
Windows 2000
Advanced Server Base, SP1, SP2, SP3, SP4 | Professional Base, SP1, SP2, SP3, SP4 | Server Base, SP1, SP2, SP3, SP4
Associated Products:
N/A
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